Two circles intersect such that their centers and their points of
intersection form a square with each side equal to 3. What is the total
area of the sections of the square that are not shared by both circles?

Mr. Brown had a square window 120cm x 120cm, but the only material he
could find was a sheet of plywood 160cm x 90cm; same area, different
shape. He drew some lines and cut out just two congruent shapes, which he
joined to make a square of the correct size. How did he do it?